Please refer to FIG. 1, a conventional clarinet 1 is lengthy and difficult to carry, and also has a slim and delicate structure, and could be out of tone upon impact, hence usually is held in a protective case for carrying to avoid impact or damage. As the case for the clarinet 1 has to match the profile thereof that results in a bulky size and not easy to carry, the wind instruments usually are disassembled in sections to be held in a case to facilitate carrying and transportation, and are assembled when in use.
The clarinet 1 has blowing orifices 2 covered by depressible finger plates that are blown by air to generate different tones. If the coupling structure of the clarinet 1 is not tightly formed, air could leak out through gaps of a coupling joint 3 in addition to delivering through the blowing orifices 2, and result in out of tone during playing. To prevent such a problem from taking place, a cork 4 is commonly disposed at the coupling joint 3 in the conventional design to avert air leakage through gaps formed at the coupling joint. The conventional clarinet 1 generally is formed at a diameter based on the temperature of frigid zone countries to smooth tight coupling of the coupling joint without forming gaps or causing tone errors. However, in countries located in the tropical zone where the temperature is higher, heat expansion increases the size of the cork 4 that makes assembly and disassembly of the clarinet 1 difficult and requiring a greater effort. It is troublesome for users without powerful physical strength. Moreover, trying to assemble and disassemble the clarinet 1 forcefully tends to damage the structure and elements of the clarinet 1.